Many countries around the world, including the United States, the European Union, Japan, and Korea, regulate the percentage by weight amount of genetically modified material (% GMO) that may be present in imported agricultural goods. In a shipment of imported agricultural goods such as, for example, corn, soybeans wheat, canola and the like, the European Union currently allows a maximum of 0.9% by weight of GMO, while Japan currently allows no more than 5%, and Korea currently imposes a limit of 3%.
When an agricultural material is harvested from a farmer's field and loaded onto a truck for shipment to a supplier, a rapid protein test is often performed on a sample of the material to determine the approximate % GMO therein. Assuming that the rapid protein test determines the % GMO of the sample is less than the required tolerance, the agricultural material is then shipped and stored temporarily in a silo before being offloaded onto a barge or other conveyance for shipment to a final destination (e.g., an ocean port).
A sample of the agricultural material is often submitted to a testing laboratory, which performs on the sample a PCR or other suitable DNA test, since this type of testing is often the official regulatory test recognized by the country designated to receive the shipment. The PCR test purports to accurately determine the % GMO present in the sample. The most common PCR test, generally known as the 35S test, evaluates the agricultural material to detect the presence of common genetic elements found in most events and allows for screening of the material.
In the PCR test, the sample is ground and genetic material is extracted. Screening tests are performed on the extracted genetic material to detect the presence of specific genetic elements, such as the 35S promoter or other specific genetic elements. Each type of agricultural material such as, for example, corn, soybeans, canola, and wheat, have specific promoters detected by the PCR screening process. For example, in a corn sample the standard 35S test screens for up to 7 specific corn promoters, and the amount of each promoter detected is summed to determine the number of transgenes in the sample. The number of transgenes is then divided by the number of control (non-genetically modified) genes in the sample to determine the percentage by weight of genetically modified material (% GMO).